Lost in Space "got campy" in its first season. It wasn't coldly serious for the whole year, and you can see the switch pretty clearly from fairly solid, straight SF adventure to wacky fantasy. The real transition from serious to comedy was The Space Croppers, when the Robinson's are visited by aliens dressed as hillbillies in a space ship that looked like a log cabin. From that episode forward, things got dicey. Suddenly Smith's comedy antics really took center stage. The main difference in season 2 was that the series became Children's Theater, with wacky monsters and colorful eccentric aliens.

I would say instead that LiS got more comical as its first season progressed, but camp is a particular flavor of comedy (characterized by irony and self-satirical excess) that I don't think the show fully embraced until season 2. The remaining first-season episodes after "The Space Croppers" still had some relatively serious elements in them, so I wouldn't say that one episode represented a pattern.

Besides, "Croppers" was episode 25 out of the 29-episode first season, so we're really only talking about a difference of five episodes. Although Smith's comedy antics had already taken center stage well over a dozen episodes earlier.